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Thursday, August 06, 2009

Hot spots for coastal freaque waves

. . . changes in water depth and currents, which are common in coastal areas, may significantly increase the likelihood of these extreme waves.

That's the suggestion from a new paper just published in the latest Journal of Physical Oceanography entitled "Nonlinear wave statistics in a focal zone" by Tim Janssen and T.H.C. Herbers. It's the results from wave model simulations. I am not generally keen on wave model simulations, but I am looking forward to find and read their paper as I know Tim Janssen from WISE meetings to be one of the brilliant young wave model scientists the Neitherland has to offer and the implications from their research does make good sense as the coastal areas which they called focal zones or hot spots do experience excessive occurrences of freaque wave acts, many led to tragedies, around the world oceans as we have frequently seen in this blog.

Surfers certainly know where great surf waves are as this picture from PerthNOW this morning shows:

Could those great places for surfing be also sites of hot spots?

Update 8/7/2009:

While most science news groups are interested in Tim Janssen's research results, local news also started reporting it, e.g. this Mecury News article today.

I wish to make a note on one point that most reporters have been interested in reporting. That is this quoted statistical comment:

"In a normal wave field, on average, roughly three waves in every 10,000 are extreme waves," Janssen said. "In a focal zone, this number could increase to about three in every 1,000 waves."

I think the case of the "normal wave field" was based on the classical theory of Rayleigh distributions, whereas the "focal zone" case is resulting from his model simulations. They are not based on actual measurements. There is hardly any actual measurement available to substantiate this kind of statistical implications. So take them with a grain of salt. It may not be immediately practicable, but actual measurements are badly needed to move the science beyond the speculations of "model simulation" stage. It is not easy, but until actual measurements are made, all these kind of big hooplas are no more than just merely speculative conjectures.

Update 8/9/2009:

BBC News joined the parade of this news story today with an article entitled "Freak wave 'hot spots' identified". The article included two nice pictures. The first one

has this caption: "The researchers fed data on real waves into a computer model." The problem is that the researchers most certainly do not have data on real waves per se. So it's only the reporter's imagination that computer model can be fed data on real waves. Where do the data on real waves come from?

The second picture is a deep sea oil production platform

with caption "The research could help inform the design of offshore platforms." The reported research, if the reporter had even paid attention at all, will know that it is for nearshore shallow waters, so clearly will do nothing to help inform the design of offshore platforms what so ever.

So if you ever think any report that's carrying a BBC label should be more authoritative or accurate -- you will be disappointed. I hope this is just an exception. But since I am fully aware that the present day main-stream media's reporting on world political matters are known to be obstinate and without objectivity, I should not be surprised but still disappointed that their indifferent and couldn't care less attitudes also carried into science reporting. BBC articles are more likely to be read and referenced. Just hope the readers have better judgment than the reporter.